The present invention relates to box end wrenches, and more particularly to such a box end wrench which has stop means adapted for holding down the bolt or nut to be turned.
A box end of a box end wrench or ratchet box end wrench or a socket for socket wrench, has a plurality of internal angles (the number of the internal angles can be 4, 6, 8, 12, 16 or 20) by which the box end can be positively attached to the bolt or nut to be turned (see FIGS. 1 and 2). However, when the wrench is turned the box end of the wrench may slip from the bolt or nut, resulting in the bolt or the nut is not to turned positively. FIGS. 3 and 5 show a wrench having a spring-supported stop ball suspended above the box of the box end and adapted for stopping the wrench from escaping out of the bolt or nut to be turned. However, this arrangement is still not satisfactory in function, because the stop ball wears quickly with use, and the spring force of the spring which supports the stop ball tends to be surpassed by the turning for applied to the wrench. FIGS. 4 and 6 show a wrench having a sliding stop plate retractably suspended above the box of the box end and adapted for stopping the wrench from escaping out of the bolt or nut to be turned. However, the arrangement of the sliding stop plate limits the maximum turning angle of each turning step of the wrench.
According to one embodiment of the present invention, a wrench is provided having a split binding ring mounted in an annular groove at internal angles of a box of a box end thereof for stopping wrench from escaping out of the bolt or nut to be turned. According to another embodiment of the present invention, a wrench is provided having a plurality of smoothly curved raised portions at internal angles of a box of a second box end thereof for stopping the wrench from escaping out of the bolt or nut to be turned.